Hydrodynamic characteristics of liquid–liquid–liquid three-phase flow in a confined microchannel

Abstract

Numerical simulations have been performed to reveal the hydrodynamic characteristics of liquid–liquid–liquid three-phase flow in a confined microchannel via a VOF-CSF model. Further the effects of outer phase flowrate, dimensions, the viscosities of all three phases as well as the interfacial tensions of both inner and outer interfaces are systematically investigated. It is found that the shear stress and pressure gradient together determine the formation and disappearance of vortices inside the compound droplets. The internal fluid velocity of compound droplets is significantly altered by the flowrate and viscosity, while the effect of interfacial tension can be ignored. As for the vorticity distribution inside the compound droplets, it exhibits a positive correlation with the capillary number of outer phase. Besides, a prediction correlation for the average velocity of compound droplets with several dimensionless numbers is also established with good precision. The results obtained in this study could provide meaningful theoretical guidance for rational design and regulation of transport behaviors with liquid–liquid–liquid three-phase flow in a confined microchannel.